The American Intercollegiate Football Association held its first
championship game on Thanksgiving Day, 1876. The sport resembled
something of a cross between rugby and modern-day football, but
the tradition of playing football on Thanksgiving Day developed
with the evolution of the sport itself.

By the 1890s, perennial favorites Yale and Princeton drew upwards
of 40,000 fans for the collegiate championship games, while more
than 5,000 club, college, and high school football games were
played on the holiday.